The mechanism
A plywood escalation clause indexes the plywood-affected portion to a published series instead of fixing it at signing. The benchmark is the BLS producer price index for Plywood, series WPU083.
Plywood is a real input cost in sheathing and subfloors, concrete formwork, and crating and packaging work. Its price can move more over a contract term than a fixed-price contingency is built to absorb, so indexing the plywood-affected portion moves that risk onto the published index instead of onto one party.
What's specific to plywood
Plywood swings with housing starts as sharply as lumber does, and sheathing grade and sanded finish grade can move in opposite directions within the same quarter. The clause should name the grade, not just "plywood".
The calculation, step by step
- Base index value. The index value at the base period, usually the month of contract signing or bid submission.
- Current index value. The index value at the adjustment date, usually the month of delivery or invoicing.
- Ratio. Current value divided by base value.
- Adjustment. Apply the ratio to the plywood-affected portion, not necessarily the whole contract.
Take a clause with a $140,000 plywood-affected scope, a base index of 260.0, and a current index of 292.0. The ratio is 1.12, a 12% increase, so $16,800 is added to that scope.
Where clauses go wrong
The most common mistake is not naming a series code. "The plywood index" is not a series. BLS publishes more than one plywood-related series, so name the exact code, WPU083, in the contract text.
Clauses also skip the averaging window. A single month's value swings more than a 3-month rolling average, so the clause should say which one applies. Publication lag gets left out the same way: BLS releases data on a delay and revises early figures, so the clause should say whether the preliminary or final value governs.
The last common gap is no cap or floor. With no cap, an index spike passes through in full, which can make a large adjustment commercially unworkable.
Related
- Escalation clause analyzer: paste a clause and see the formula, undefined terms, and risk score.
- How escalation clause base periods work
- Price adjustment caps and floors